fcase {data.table}

fcase

Description

fcase is a fast implementation of SQL CASE WHEN statement for R. Conceptually, fcase is a nested version of fifelse (with smarter implementation than manual nesting). It is comparable to dplyr::case_when and supports bit64's integer64 and nanotime classes.

Usage

  fcase(..., default=NA)

Arguments

...

A sequence consisting of logical condition (when)-resulting value (value) pairs in the following order when1, value1, when2, value2, ..., whenN, valueN. Logical conditions when1, when2, ..., whenN must all have the same length, type and attributes. Each value may either share length with when or be length 1. Please see Examples section for further details.

default

Default return value, NA by default, for when all of the logical conditions when1, when2, ..., whenN are FALSE or missing for some entries.

Value

Vector with the same length as the logical conditions (when) in ..., filled with the corresponding values (value) from ..., or eventually default. Attributes of output values value1, value2, ...valueN in ... are preserved.

See Also

fifelse

Examples

x = 1:10
fcase(
	x < 5L, 1L,
	x > 5L, 3L
)

fcase(
	x < 5L, 1L:10L,
	x > 5L, 3L:12L
)

# Lazy evaluation example
fcase(
	x < 5L, 1L,
	x >= 5L, 3L,
	x == 5L, stop("provided value is an unexpected one!")
)

# fcase preserves attributes, example with dates
fcase(
	x < 5L, as.Date("2019-10-11"),
	x > 5L, as.Date("2019-10-14")
)

# fcase example with factor; note the matching levels
fcase(
	x < 5L, factor("a", levels=letters[1:3]),
	x > 5L, factor("b", levels=letters[1:3])
)

# Example of using the 'default' argument
fcase(
	x < 5L, 1L,
	x > 5L, 3L,
	default = 5L
)